The objective of the proposed Phase I research program is to establish the feasibility of operating in a dry dental field, using a self-cooled drill which does not require a water spray. Specific aims are to show that a self-cooled drill can be designed to conform to the requirements of accepted dental operative practice, and that use of the drill will not cause excessive temperatures and consequent damage to tooth tissue. These goals are to be achieved by: 1. Establishment of operative, thermal, and technical criteria for conducting the proposed effort, through a literature review and consultation with practicing dental clinicians. 2. Heat transfer and structrual studies to determine design and performance characteristics of a self-cooled dental drill. 3. Studies of temperature response in pulpal tissue during cavity preparation with the self-cooled dental drill. 4. Definition of Phase II plan for experimental verification of concept feasibility and compatibility with current dental operative practice. Results of the Phase I effort will provide the basis for the design, manufacture, and evaluation of self-cooled dental equipment in Phase II. If successful, the proposed research will establish the practicality of an important new class of dental cutting instruments. A substantial market for self-cooled drills in the dental profession can then be anticipated.